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Numerical Simulation of Oscillating Fluid Flow in Inertance Tubes

C. Dodson1, A. Razani2, T. Roberts3
1Spacecraft Component Thermal Research Group, Kirtland AFB, NM 87117 USA, 2The University of New Mexico, Albuquerque, NM 87131 USA; Applied Technology Associates, Albuquerque, NM 87123 USA, 3Air Force Research Laboratory, Kirtland AFB, NM

Abstract

Inertance tubes are used in Pulse Tube Refrigerators (PTRs) to control the phase shift between the mass flow and pressure to increase performance of the refrigerator. Computational Fluid Dynamics (CFD) simulation of the oscillating fluid flow in the inertance tube for different tube geometries is presented in this study. Commercial CFD code FLUENT is used to carry out the simulations. The results of CFD simulations are compared to the available experimental results. In addition, the results of grid convergence studies, important in any numerical simulation, are presented and discussed. A numerical model is developed by dividing the inertance tube into sections where the conventional first order model is used in each section. The resulting simultaneous non-linear Ordinary Differential Equations (ODEs) are solved numerically to determine the input acoustic power and the phase shift between mass flow and pressure at the inlet of the inertance tube. The results of the first order model and CFD simulation are compared and discussed.